Light fixtures have been in use essentially ever since the introduction of electricity as a source of power in buildings and other environments. Modern light fixtures typically include at least one light source (such as an incandescent or fluorescent lamp) and a housing that supports and/or encloses the light source and connects it to an electrical power source (e.g. through a light socket and wiring.) They may be attached to ceilings, walls, or other parts of building structures, and may also be combined with other electrically powered components. For example, the combination of a light fixture and a fan fixture (e.g. a ceiling fan) is common used to provide fan/light combination fixtures.
Typically, light fixtures have some limitations (e.g. due to their structure or design) on the amount of current and/or temperature they can sustain under normal, safe, and/or otherwise desirable operating conditions. For example, many light fixtures are designed to safely sustain the current and temperature that typically results during the operation of one or more 60 watt bulbs connected to a 120 volt power source. Such safe operating limits (also described as ratings) are typically labeled on the light fixture to inform the user.
However, a light source which operation may cause a higher than rated current and/or temperature to occur in a light fixture (e.g. a 75 watt bulb substituted for a 60 watt rated bulb) can usually be installed, whether intentionally (e.g. to obtain more light) or accidentally as an oversight. Such operation of a light fixture with a larger light source than it is rated to handle may result in abnormal, unsafe, or otherwise undesirable conditions, which can cause a loss of operation and significant damage to the light fixture and the surrounding environment, e.g. due to excessive heat, smoke, and/or fire.
Heretofore many devices have been used to limit current flow to loads including light fixtures and ballasts. For example, thermisters have been used as sensors to trigger an electronic cutoff switch should current flow through it exceed a preselected level. Positive temperature coefficient switches or PTCs have also been so used. Triacs and relays have also been employed. These devices and circuits however usually require their own power source and consume power. This may be avoided with a PTC switch but only at the expense of a generation of significant heat. These circuits are also relatively costly for the passive role they normally play.
Circuit interrupters like fuses and circuit breakers are of course used in building circuits that service light fixtures. The fixtures themselves may also employ such together with a reset button. Operation of these however completely extinguishes the light which can create a hazardous situation. When the fixture is elevated, as in the case of a ceiling light or ceiling fan with lights, manual operation of the reset button will often require access to a stepladder.
It thus is seen that a need exists for an apparatus and method of controlling the power consumption of a light fixture to avoid damage or complete loss of operation without extinguishing it when a higher than rated light source is used deliberately or by oversight in the light fixture. It is to the provision of such that the present invention is primarily directed.